You may base your regexp on this: (This one matches ), but not those following '. )

$s = "(abcd')'1234)";
$s =~ m/(\(.*?(?<!\')\))/;
print $1;
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Be careful, I took two assumptions, which fit your sample data:

1. there is no \'(backslash quot)
2. if you have ) in quots, it always comes right after the '